Microreaction and membrane technologies offer optimal conditions for controlling enantiomer synthesis and purification processes in continuous production, with numerous advantages over batch manufacturing. One of the many forces driving the development of such technologies for the production of single optical isomers is the need for enantiomerically pure pharmaceutical drugs because enantiomers may display opposite therapeutic effects or different treatment efficacies and side effects. Yet, despite advances in asymmetric synthesis and separation techniques, preparing enantiomerically pure compounds remains a challenging task. Here, we review the progress in microfluidics and membrane chiral separation over the last two decades. In addition to describing and critically assessing the state of the art in both disciplines, we provide an overview of their beneficial properties and characteristics for developing technologies toward producing enantiomerically pure compounds. Concomitantly, we evaluate efforts to integrate synthesis and membrane separation into a microfluidic platform and pinpoint the limiting factors that must be overcome before these platforms can be fully deployed in the industry.

Electrodialysis and electrodeionization are separation processes whose performance depends on the quality and properties of ion-exchange membranes. One of the features that largely affects these properties is heterogeneity of the membranes both on the macroscopic and microscopic level. Macroscopic heterogeneity is an intrinsic property of heterogeneous ion-exchange membranes. In these membranes, the functional ion-exchange component is dispersed in a non-conductive binder. The functional component is finely ground ion-exchange resin particles. The understanding of the effect of structure on the heterogeneous membrane properties and behavior is thus of utmost importance since it does not only affect the actual performance but also the cost and therefore competitiveness of the aforementioned separation processes. Here we study the electrokinetic behavior of cation-exchange resin particle systems with well-defined geometrical structure. This approach can be understood as a bottom up approach regarding the membrane preparation. We prepare a structured cation-exchange membrane by using its fundamental component, which is the ion exchange resin. We then perform an experimental study with four different experimental systems in which the number of used cation-exchange particles changes from 1 to 4. These systems are studied by means of basic electrochemical characterization measurements, such as measurement of current–voltage curves and direct optical observation of phenomena that occur at the interface between the ion-exchange system and the adjacent electrolyte. Our work aims at better understanding of the relation between the structure and the membrane properties and of how structure affects electrokinetic behavior of these systems.